Nitrogen injection assembly for use in an optical fiber coloring and curing apparatus

ABSTRACT

A nitrogen injection assembly for use in coloring and curing optical fibers is disclosed. The nitrogen injection assembly includes a cover section and a distribution seal. An optical fiber coated with ink passes from a coating die to a curing chamber via a passageway defined by the cover section and the distribution seal. The distribution seal injects nitrogen into the passageway to keep the coated fiber and the curing chamber substantially free of oxygen. With the distribution seal positioned closer to the curing chamber than the cover section, the apparatus minimizes the risk of leaks in the passageway and the number of required seals.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is an U.S. National Phase Application based onPCT/US02/31551, filed Oct. 3, 2002, the content of which is incorporatedherein by reference, and claims the benefit of U.S. ProvisionalApplication No. 60/327,229, filed Oct. 5, 2001.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus for applying and curingink on optical fibers. More particularly, the present invention relatesto an improved nitrogen injection assembly for use with a coating dieassembly that applies ink to an optical fiber and a curing chamber thatcures the ink with ultraviolet (UV) radiation.

Optical fibers are often colored to improve their identification andindexing. For example, a telecommunications worker can more easilydistinguish one optical fiber from another when making splices betweenoptical fiber cables if the fibers have distinctive colors.

The process for coloring optical fibers entails two basic steps. First,during the manufacture of the optical fiber, the drawn fiber is coatedwith ink by passing it through a coloring die assembly. Second, the inkis cured by passing the coated fiber through a chamber of UV radiation.Generally, this process is used for both individual optical fibers andfor optical fibers that are formed into ribbons.

Inks used for coloring optical fibers typically do not adhere properlyto optical fibers in the presence of oxygen. Consequently, the coloringinks are typically cured on optical fibers in a nitrogen environment. Toensure the absence of oxygen from the curing process, a nitrogeninjection assembly is positioned between the coating die assembly andthe UV curing chamber. The nitrogen injection assembly provides apassageway for the optical fiber between the coating die assembly andthe curing chamber. An upper portion of the nitrogen injection assemblyadds nitrogen to the passageway.

A lower portion of the nitrogen injection assembly is typically definedby a telescoping tube. In a setup mode, the telescoping tube iscollapsed to provide access to the optical fiber. After-threading theoptical fiber through the coloring die, an operator can access the fiberand attach it to a leader. The leader helps pull the fibers through theoptical fiber coloring and curing apparatus. In an operating mode, thetelescoping tube is extended to create a cylindrical passageway for theoptical fiber between the nitrogen injection assembly and the curingchamber. Various seals ensure an airtight connection, keeping innitrogen and keeping out oxygen from the ambient environment.

FIG. 1 illustrates a conventional nitrogen injection assembly for use incoating and curing ink on an optical fiber. This nitrogen injectionassembly 100 generally comprises a nitrogen injection ring 108 mountedto the underside of a coloring die mounting plate 104. Coloring diemounting plate 104, which is part of a coloring die assembly, andnitrogen injection ring 108 both have central bores through which thedrawn fiber passes. Nitrogen gas is injected into the bore in nitrogeninjection ring 108 through a side port 152.

Below nitrogen injection ring 108 is a telescope tube. The tube includesa telescope tube holder ring 112 proximate to nitrogen injection ring108. Holder ring 112 has a central bore that matches the bores ofcoloring die mounting plate 104 and nitrogen injection ring 108. Theoptical fiber passes through the central bore in holder ring 112. Bothholder ring 112 and nitrogen injection ring 108 are attached to coloringdie mounting plate 104 via screws or bolts in first threaded mountinghole 132, second screw hole 136, and third screw hole 140.

The telescope tube itself is made of a stationary telescope tube 116 anda sliding telescope tube 120. The sliding telescope tube 120, which hasa larger diameter, fits around and slides over stationary telescope tube116. By sliding telescope tube 120 up in a retracted position overstationary telescope tube 116, an operator can gain access to the fiberto attach it to a leader. When sliding telescope tube 120 is extended,it contacts a base 124 to create a sealed environment for the nitrogento travel into the curing chamber (not shown). Base 124 has a centralbore matching that of the telescope tube assembly and is mounted to thecuring chamber (not shown).

During operation, when sliding telescope tube 120 is extended, nitrogeninjection assembly 100 adds nitrogen via port 152 to the central boresdefined by nitrogen injection ring 108, stationary tube 116, slidingtube 120, and base 124. The nitrogen in general flows downwardly withthe moving optical fiber through these bores and into the curingchamber. Because the nitrogen gas is injected near the top of nitrogeninjection assembly 100, potential leak points must be sealed to ensurethe absence of oxygen from the UV curing chamber. If leaks exist, oxygenfrom the ambient atmosphere may be drawn into the nitrogen injectionassembly 100, possibly via a Ventura effect, as the nitrogen travelsdown the bore and into the UV curing chamber.

O-rings 156, 160, 164, 168, 172 and 176 seal the components of nitrogeninjection assembly 100 at various potential leak points. A first O-ring156 is positioned between coloring die mounting plate 104 and nitrogeninjection ring 108. A second O-ring 172 is positioned between holderring 112 and nitrogen injection ring 108. Third and fourth O-rings 160and 164 are positioned between the outer diameter of stationarytelescope tube 116 and the inner diameter of sliding telescope tube 120.A fifth O-ring 168 is located between base 124 and the inner diameter ofsliding telescope tube 120. A sixth O-ring 176 is positioned betweenbase 124 and a UV oven 128.

Applicants have found that this conventional nitrogen injection assemblyhas a few disadvantages. The number of potential leak points and thenumber of O-rings makes the assembly particularly susceptible to ambientair leaks that can disrupt the curing process. These O-rings are notquickly and easily repaired. Additionally, the assembly hampersefficient setup for the coating process. In particular, the spaceprovided by sliding telescope tube 120 is relatively confined for anoperator to attach a leader to the drawn fiber. Consequently, the riskof breaking a fiber is often higher than desired.

A second prior art configuration is illustrated by Japanese Patent No.4-342445. The apparatus disclosed in JP 4-342445 provides for thecoloring of an optical fiber in an oxygen-free environment. A“connection means,” located between a coating apparatus and a curingoven, forms a sealed cylindrical conduit for passing an optical fiber.In this prior art configuration, the optical fiber is coated withuncured dye, passed through the “connection means,” and fed into thecuring chamber—all in an environment containing pure nitrogen. In thismanner, the connection means of JP 4-342445 forms an air-tight sealbetween the coating apparatus and the curing oven allowing the entirecoating and curing process to be performed in an oxygen-freeenvironment.

The apparatus disclosed in JP 4-342445 suffers from many of the samedisadvantages as the prior art apparatus disclosed in FIG. 1. Inaddition, this conventional nitrogen injection assembly unnecessarilyprevents the exposure of uncured dye to oxygen.

SUMMARY OF THE INVENTION

In accordance with the present invention, an apparatus for coloring andcuring ink on an optical fiber prevents the coated fiber from beingexposed to oxygen as it passes into a curing chamber while minimizingthe number of seals and potential leak points. Applicants havediscovered that the location in which nitrogen is injected into theapparatus affects the likelihood of ambient air degrading the quality ofthe coating and curing process.

In one aspect consistent with the general principles of the presentinvention, an apparatus for coloring and curing an optical fiber thatpasses in a downstream direction during manufacture includes a coloringassembly for depositing an ink on the optical fiber, a cover section, adistribution seal, and a UV curing assembly.

The cover section is positioned downstream from the coloring assemblyand has an interior surface and an exterior surface. The interiorsurface of the cover section at least partially encloses and defines afirst duct that is configured to pass the coated optical fiber. Thecover section is configured to enable access to the coated opticalfiber. In one alternative, the cover section includes a first axialtelescope portion and a second axial telescope portion. In anotheralternative, the cover section includes a first radial or half-tubeportion and a second radial or half-tube portion. In a thirdalternative, the cover section is a flat plate.

The distribution seal of the apparatus is positioned downstream from thecover section and has an interior surface, an exterior surface, and aninlet port. The interior surface of the distribution seal at leastpartially defines a first bore that is configured to pass the opticalfiber received from the cover section. The inlet port extends from theexterior surface of the distribution seal to the interior surface. It isadapted to flow nitrogen into the first bore.

As well, a lead-in piece may be positioned between the distribution sealand the cover section. The lead-in piece has an interior surface and anexterior surface. The interior surface of the lead-in piece at leastpartially encloses a second bore capable of passing the coated opticalfiber between the first duct of the cover section and the first bore ofthe distribution seal.

Finally, the UV curing assembly is positioned downstream from thedistribution seal. It receives the coated optical fiber from thedistribution seal and cures it in an oxygen-free environment.

The arrangement of components permits easy access to the optical fiberduring setup and minimizes a risk of oxygen leaks during operation. Withthe distribution seal positioned downstream from the cover section, theapparatus can ensure that nitrogen surrounds the coated fiber as itenters the curing assembly while using a minimum number of seals.

In a second aspect, a nitrogen injection assembly for use in anapparatus for coloring and curing optical fibers that is consistent withthe principles of the present invention includes a cover section and adistribution seal. The apparatus includes a color coating die and acuring chamber.

The cover section has an interior surface and an exterior surface. Theinterior surface at least partially encloses a first duct that iscapable of passing a coated optical fiber.

The distribution seal is located closer to the curing chamber than thecover section. It has an interior surface, an exterior surface, and aninlet port. The interior surface of the distribution seal at leastpartially defines a first bore that is capable of passing the coatedoptical fiber. The inlet port extends from the exterior surface of thedistribution seal and is adapted to allow nitrogen to flow into thefirst bore. The first bore is aligned axially with the first duct of thecover section.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are intended to provide further explanation of the invention asclaimed. The following description, as well as the practice of theinvention, set forth and suggest additional advantages and purposes ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute partof this specification, illustrate several embodiments of the inventionand together with the description, serve to explain the principles ofthe invention.

FIG. 1 is an exploded cross-sectional view of a conventional nitrogeninjection assembly for use in coating and curing ink on an opticalfiber;

FIG. 2 is an exploded cross-sectional view of an embodiment of anitrogen injection assembly consistent with the principles of thepresent invention;

FIG. 3 is a top-level view of a distribution seal of the nitrogeninjection assembly shown in FIG. 2;

FIG. 4 is a cross-sectional view of the distribution seal of FIG. 3;

FIG. 5 is a top-level view of a lead-in piece of the nitrogen injectionassembly shown in FIG. 2;

FIG. 6 is a cross-sectional view of the lead-in piece of FIG. 5;

FIG. 7 is a top-level view of a cover section of the nitrogen injectionassembly shown in FIG. 2;

FIG. 8 is a front view of the cover section of FIG. 7;

FIG. 9 is a perspective view of another embodiment for the cover sectionand lead-in piece consistent with the principles of the presentinvention; and

FIG. 10 is a cross-sectional view of the combined cover section andlead-in piece of FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to various embodiments according to thisinvention, examples of which are shown in the accompanying drawings andwill be obvious from the description of the invention. In the drawings,the same reference numbers represent the same or similar elements in thedifferent drawings whenever possible.

Consistent with the general principles of the present invention, anapparatus for coating and curing ink on an optical fiber includes acoloring assembly, a cover section, a distribution seal, and a UV curingassembly. As herein embodied and illustrated in FIG. 2, an apparatus 200for coloring and curing an optical fiber includes a die mounting plate220, cover section 212, lead-in piece 208, distribution seal 204, and UVoven 216.

Die mounting plate 220 is part of a larger coloring assembly (notshown). An optical fiber (not shown) is introduced into the coloringassembly after having been drawn in a conventional optical-fibermanufacturing process. The coloring assembly includes at least a coatingdie for applying radiation-curable ink to the optical fiber and diemounting plate 220. Various inks and techniques for applying the inkwithin a coloring assembly are within the knowledge of those of ordinaryskill in the art and may be used without deviating from the scope of thepresent invention. In FIG. 2, die mounting plate 220 represents the lastcomponent of the coloring assembly that the coated optical fiber passesthrough.

Following die mounting plate 220 is a cover section 212. As explained inmore detail below, cover section 212 is adapted to pass an optical fiber(not shown). It includes an interior surface and an exterior surface,where the interior surface at least partially defines a first duct orpassageway 244 for the coated optical fiber leaving the coloringassembly. First duct 244 and cover section 212 are both preferablycylindrical in shape.

As shown in FIG. 2, a lead-in piece 208 and a distribution seal 204 arepositioned below cover section 212. Lead-in piece 208 is preferably madeof aluminum but can be made of any other material. Lead-in piece 208defines a bore 232, which allows the optical fiber leaving cover section212 to pass. Bore 232 of lead-in piece 208 can be a straight bore or maybe tapered, as shown in FIG. 2. If tapered, bore 232 has a largeropening at the top of lead-in piece 208. In this configuration, thediameter of first duct 244 is substantially the same as an outerdiameter of the top of lead-in piece 208 so that cover section 212 canfit over the top of lead-in piece 208. First duct 244 of cover section212 is in substantial axial alignment with bore 232 of lead-in piece208. In this manner, first duct 244 and bore 232 form a continuouspassageway for an optical fiber.

Distribution seal 204 is positioned below lead-in piece 208 along theoptical fiber path. Distribution seal 204, like cover section 212 andlead-in piece 208, can be machined from aluminum, or can be convenientlymade from any other suitable material. It has an interior surface thatat least partially defines a bore 240 capable of passing the coatedoptical fiber. In addition, distribution seal 204 may include a circularchannel 236 positioned concentrically with an upper section of the bore240. Conduits 248 may be formed in distribution seal 204 betweencircular channel 236 and bore 240.

Distribution seal 204 contains an inlet port 224 that allows theintroduction of nitrogen and possibly other gases into bore 240. Inletport 224 is preferably perpendicular to the axis of bore 240 but may beinstalled at any convenient angle. Preferably, inlet port 224 isconnected to bore 240 by way of circular channel 236 and a plurality ofconduits 248. That is, nitrogen gas introduced through inlet port 224can flow into bore 240 after flowing through circular channel 236 andone or more of conduits 248. Alternatively, distribution seal 204 may beconstructed so that inlet port 224 feeds nitrogen directly into bore240. Inlet port 224 may be threaded to enable a nitrogen gas source tobe connected quickly and easily. While a specific example is shown inFIG. 2, inlet port 224 can be located in any convenient manner such thatnitrogen is permitted to enter bore 240.

Lead-in piece 208 may be affixed securely to distribution seal 204 withthe aid of O-ring 228. In this manner, an airtight seal can be achievedbetween bore 232 and bore 240, and the two bores can form a continuous,sealed passageway for the coated optical fiber. Distribution seal 204may similarly be affixed to UV oven 216 or other elements may beinserted in between. In this configuration, a bottom surface of thelead-in piece 208 may cover the top of the circular channel 236 so thata closed passageway is formed for the passage of nitrogen gas.Alternatively, a bottom surface of cover section 212 may cover an opentop portion of the circular channel 236 so that a closed passageway isformed for the passage of nitrogen gas. In this configuration, nitrogeninjection assembly 200 may comprise distribution seal 204 and coversection 212.

With the coating and curing apparatus illustrated in FIG. 2, a coatedoptical fiber can be shielded from ambient atmosphere when entering thecuring chamber with a minimized risk of leaks. In operation, an opticalfiber can pass from die mounting plate 220, through duct 244, throughbore 232, through bore 240, and into curing chamber 252 in onecontinuous flow. Nitrogen gas would be injected through port 224 ofdistribution seal 204. As mentioned above, the nitrogen would pass intochannel 236, downward through conduits 248, and into bore 240. Beingspaced around channel 236, conduits 248 help to disperse the nitrogen asit enters bore 240. The proximity of distribution seal 204 to UV oven216 helps to maintain a concentrated nitrogen atmosphere at the entranceto the curing chamber 252. Some nitrogen also flows upward in bore 240into bore 232 of lead-in piece 208 and into first duct 244 of coversection 212. A minimum number of seals is required to secure thenitrogen environment in apparatus 200, such as O-ring 228 and possibleseals (not shown) between cover section 212 and lead-in piece 208 andbetween cover section 212 and die mounting plate 220.

While the arrangement depicted in FIG. 2 is one embodiment of thepresent invention, other arrangements are within the knowledge of thoseskilled in the art. For example, lead-in piece 208 and distribution seal204 could be made as a single piece. In this manner, an embodiment ofthe present invention would include two different components, one ofwhich could be a cover section 212 and the other of which could be asingle component which performs the functions of distribution seal 204and lead-in piece 208. In yet another embodiment of the presentinvention, a single component can comprise distribution seal 204,lead-in piece 208, and cover section 212. In this fashion, an embodimentof the present invention would include a single component which performsthe functions of distribution seal 204, lead-in piece 208, and coversection 212.

FIGS. 3 and 4 respectively illustrate top and side cross-sectional viewsof distribution seal 204. As shown in these drawings, distribution seal204 has an exterior circumferential surface 304, an interior surface308, a channel 236, a bore 240, and a plurality of conduits 248.Distribution seal 204 may also have a bottom surface 428 and a topsurface 432. Bore 240 can extend from top surface 432 throughdistribution seal 204 to bottom surface 428. In this manner, bore 240can be bounded by interior surface 308. Bore 240 may include an upperbore 416 and a lower bore 420. In this embodiment, upper bore 416 canhave a smaller diameter than lower bore 420 and extend approximatelyhalfway between top surface 432 and bottom surface 428. Lower bore 420could extend from bottom surface 428 to approximately halfway betweentop surface 432 and bottom surface 428. Upper bore 416 is in substantialaxial alignment with lower bore 420 so that upper bore 416 and lowerbore 420 form a continuous passageway for an optical fiber. Preferably,bore 240, upper bore 412, and lower bore 420 are cylindrical.

Channel 236 could be machined into top surface 432 of distribution seal204. Of course, channel 236 can be formed into top surface 432 ofdistribution seal 204 in any manner. Channel 236 can be circumferentialin form and concentric with upper bore 416. A plurality of conduits 248extend from channel 236 to lower bore 420. In this manner, a continuousopening may be formed through channel 236, through a plurality ofconduits 248, and into lower bore 420.

Inlet port 224 extends from exterior circumferential surface 304 tochannel 436. In a further embodiment, inlet port 224 could extend fromexterior circumferential surface 304 directly to bore 240. Inlet port224 is adapted so that nitrogen and possibly other gases can flowthrough inlet port 224, through channel 236, through a plurality ofconduits 248, through lower bore 420, and through upper bore 416. Itwould be readily apparent to one skilled in the art that otherarrangements exist for the flow of gas through inlet port 224 and intobore 240.

Referring now to FIGS. 5 and 6, FIG. 5 illustrates a top view of lead-inpiece 208, and FIG. 6 represents a cross-sectional view of lead-in piece208 in one embodiment of the present invention. In FIG. 6, bore 232,which may be bounded by interior surface 508, is depicted as beingtapered. In this embodiment of the present invention, an upper crosssection of bore 232 has a greater diameter than a lower cross section ofbore 232. Bore 232 need not be tapered but may be of any shape thatallows the passage of an optical fiber. Preferably, lead-in piece 208also comprises flange 614. In this manner, an upper diameter of ahorizontal-cross section of lead-in piece 208 may be smaller than alower diameter of a horizontal cross section of lead-in piece 208.Flange 614, for example, can be attached to a top surface ofdistribution seal 204 of FIG. 2. In this configuration, a bottom surfaceof lead-in piece 208 may cover the channel 236 of distribution seal 204.

Referring now to FIGS. 7 and 8, FIG. 7 depicts a top view of coversection 212, and FIG. 8 depicts a side view of cover section 212. Coversection 212 may be a distinct component or it may be an integral portionof the lead-in piece 208. In FIG. 7, cover section 212 is comprised offirst radial or half tube section 704 and a second radial or half tubesection 708. When connected together in a closed position, first halftube section 704 and second half tube section 708 form a closed duct 244for the passage of an optical fiber. Connection groove 712 is shown asan example of a connection that may occur between first half section 704and second half section 708. Additionally, first half tube section 704and second half tube section 708 may be connected together in a varietyof ways, for example, by a hinge, a seal, or, as shown in FIG. 7, aconnection groove 712.

Referring now to FIG. 8, cover section 212 has a top surface 812 and abottom surface 816. A first duct 244 extends from top surface 812through cover section 212 to bottom surface 816. In this embodiment,first half tube section 704 and second half tube section 708 can bejoined together with clasp 812.

It would be obvious to one skilled in the art that other shapes forcover section 212 would readily function in the present invention. Whilea cylindrical cross-section is preferred, cover section 212 could have asquare, elliptical, or polygonal cross section. Moreover, cover section212 need not be of any particular length other than that determined forthe application. In this manner, cover section 212 need not extendcompletely up to connect with die mounting plate 220 of FIG. 2.

In a further embodiment of the present invention, the cover section 212as depicted in FIG. 2 can comprise two telescoping tubes. Similar totubes 116 and 120 in FIG. 1, a first telescoping tube can be arranged toslide over a second telescoping tube. In this manner, one of thetelescoping tubes can slide up and over the other telescoping tube. Whenused in the present invention, sliding one telescoping tube up over thesecond telescoping tube can provide access to the optical fiber so thata leader can be attached during a setup mode for the system. Due to theplacement of cover section 212 upstream from distribution seal 204, thetelescoping tube assembly for cover section 212 could be constructedwithout any, or with few, O-rings.

FIG. 9 depicts a variation consistent with the principles of the presentinvention where cover section 212 and lead-in piece 208 are combinedinto a single component 900. FIG. 10 depicts a cross sectional view ofcomponent 900. Lead-in piece 208 can have a flange 614 which can beused, for example, to attach lead-in piece 208 to distribution seal 204.

As shown in FIG. 10, cover section 212 may be integrally connected tothe top surface of lead-in piece 208 to form component 900. In thisembodiment, cover section 212 is a flat plate with a first duct 244. Theopening of duct or ducts 244 is relatively constrained to prohibitambient air from passing downward into the nitrogen injection assemblywith the optical fiber. A sufficient flow of nitrogen is made to passupwardly through duct 244 to prevent the ingress of oxygen. In theembodiment depicted in FIGS. 9 and 10, first duct 244 is configured toaccept four optical fibers, though any number may be accepted in otherembodiments of the present invention. Bore 232 extends from a topsurface of lead-in piece 208 to a bottom surface of lead-in piece 208.While bore 232 is shown as tapered, it could have any shape permitted bythe particular application in which it is used. Lead-in piece 208 alsocomprises flange 614 for attaching it to distribution seal 204.

In the embodiment in which cover section 212 is formed of a flat plate,access to the optical fibers during setup may occur above the plate.That is, depending on the configuration required for the particular use,a gap is left between cover section 212 and die mounting plate 220.Preferably, this gap extends about six inches from cover section 212 todie mounting plate 220. In this gap, an operator or craftsman can accessthe optical fiber after threading the coating die and attach a leader tohelp pull the fiber through the entire coating and curing apparatus.

In a further embodiment of the present invention, distribution seal 204,lead-in piece 208, and cover section 212 may form a single component(not shown). This component (not shown), like component 900, can includea cover section 212 in the form of a flat plate as depicted in FIGS. 9and 10.

It should be noted that other components and structures may be employedwith the nitrogen injection assembly of this invention without departingfrom the spirit and scope of the invention. Such components andstructures may include various mounting plates, ring holders, and otherelements as known by those skilled in the art.

It should be understood that the foregoing relates only to the exemplaryembodiments of the present invention. For example, variations in theshape or configuration of the bores and ducts that form a passageway arenot restricted by the particular examples illustrated and describedherein. Namely, the disclosed apparatus may be configured to permit thecoating and curing of ink on more than one optical fiber at a time.Numerous changes may be made thereto without departing from the scope ofthe invention as defined by the following claims.

1. A nitrogen injection assembly for use in an apparatus for coloringand curing optical fibers, the apparatus including a color coating dieand a curing chamber, the nitrogen injection assembly comprising: acover section separated from the color coating die, the cover sectionhaving an interior surface and an exterior surface, the interior surfaceof the cover section at least partially enclosing a first duct capableof passing a coated optical fiber; and a distribution seal locatedcloser to the curing chamber than the cover section and having aninterior surface, an exterior surface, and an inlet port, the interiorsurface of the distribution seal at least partially defining a firstbore capable of passing the coated optical fiber, the first bore beingaligned axially with the first duct of the cover section and includingupper and lower cylindrical sections, the upper cylindrical sectionhaving a smaller diameter than the lower cylindrical section, whereinthe distribution seal includes a circular channel concentric with theupper cylindrical section of the first bore, and wherein the inlet portextends between the exterior surface of the distribution seal and thecircular channel and is adapted to allow nitrogen to flow into the firstbore.
 2. The nitrogen injection assembly of claim 1, further comprisinga lead-in piece positioned between the distribution seal and the coversection, the lead-in piece having an interior surface and an exteriorsurface, the interior surface of the lead-in piece at least partiallyenclosing a second bore capable of passing the coated optical fiberbetween the first duct and the first bore.
 3. The nitrogen injectionassembly of claim 2, wherein the lead-in piece has a circular topsurface and a circular bottom surface, the second bore having asubstantially same diameter at the circular bottom surface as an upperportion of the first bore of the distribution seal.
 4. The nitrogeninjection assembly of claim 2, wherein the lead-in piece is affixed tothe distribution, substantially preventing entry of ambient atmosphereinto the first and second bores.
 5. The nitrogen injection assembly ofclaim 4, wherein a bottom portion of the lead-in piece forms a flange.6. The nitrogen injection assembly of claim 2, wherein the lead-in piecehas a circular top surface and a circular bottom surface, a diameter ofthe top surface being less than a diameter of the bottom surface, thesecond bore of the lead-in piece extending from the circular top surfaceto the circular bottom surface.
 7. The nitrogen injection assembly ofclaim 2, wherein the second bore of the lead-in piece is tapered.
 8. Thenitrogen injection assembly of claim 2, wherein the cover section is aflat plate mounted on top of the lead-in piece.
 9. The nitrogeninjection assembly of claim 1, wherein the distribution seal includes aplurality of conduits between the circular channel and the lower bore.10. The nitrogen injection assembly of claim 1, wherein the coversection is configured to enable access to the coated optical fiber. 11.The nitrogen injection assembly of claim 10, wherein the separationbetween the cover section and the color coating die provides access tothe coated optical fiber.
 12. The nitrogen injection assembly of claim10, wherein the cover section comprises a first axial telescope portionand a second axial telescope portion, the second axial telescope portionbeing slidable at least partially within the first axial telescopeportion.
 13. The nitrogen injection assembly of claim 10, wherein thecover section comprises a first radial portion and a second radialportion, the first duct of the cover section being formed by alignmentof at least the first and second radial portions.
 14. A nitrogeninjection assembly for use in an apparatus for coloring and curingoptical fibers, the apparatus including a color coating die and a curingchamber, the nitrogen injection assembly comprising: a cover sectionseparated from the color coating die, the cover section having aninterior surface and an exterior surface, the interior surface of thecover section at least partially enclosing a first duct capable ofpassing a coated optical fiber; a distribution seal located closer tothe curing chamber than the cover section and having an interiorsurface, an exterior surface, and an inlet port, the interior surface ofthe distribution seal at least partially defining a first bore capableof passing the coated optical fiber, the first bore being alignedaxially with the first duct of the cover section and including upper andlower cylindrical sections, the upper cylindrical section having asmaller diameter than the lower cylindrical section, wherein thedistribution seal includes a circular channel concentric with the uppercylindrical section of the first bore and a plurality of conduitsextending between the circular channel and the lower bore, and whereinthe inlet port extends between the exterior surface of the distributionseal and the circular channel and is adapted to allow nitrogen to flowinto the first bore; and a lead-in piece positioned between thedistribution seal and the cover section, the lead-in piece having aninterior surface and an exterior surface, the interior surface of thelead-in piece at least partially enclosing a second bore capable ofpassing the coated optical fiber between the first duct and the firstbore, wherein a bottom surface of the lead-in piece covers an open topportion of the circular channel.
 15. An apparatus for coloring andcuring an optical fiber passing in a downstream direction duringmanufacture, comprising: a coloring assembly for depositing an ink onthe optical fiber; a cover section separated from the coloring assemblyby an air gap and having an interior surface and an exterior surface,the interior surface of the cover section at least partially enclosing afirst duct configured to pass the optical fiber; a distribution sealpositioned downstream from the cover section and having an interiorsurface, an exterior surface, and an inlet port, the interior surface ofthe distribution seal at least partially defining a first boreconfigured to pass the optical fiber, the inlet port extending from theexterior surface of the distribution seal to the interior surface of thedistribution seal and being adapted to flow nitrogen into the firstbore, wherein the first bore defined by the interior surface of thedistribution seal includes upper and lower cylindrical sections, theupper cylindrical section having a smaller diameter than the lowercylindrical section, wherein the distribution seal includes a circularchannel concentric with the upper cylindrical section of the first bore,and wherein the inlet port extends between the exterior surface of thedistribution seal and the circular channel; and a UV curing assemblypositioned downstream from the distribution seal.
 16. The optical fibercoloring and curing apparatus of claim 15, further comprising a lead-inpiece positioned between the distribution seal and the cover section,the lead-in piece having an interior surface and an exterior surface,the interior surface of the lead-in piece at least partially defining asecond bore, the second bore being in substantial axial alignment withthe first bore of the distribution seal.
 17. The optical fiber coloringand curing apparatus of claim 15, wherein the cover section isconfigured to enable access to the coated optical fiber.
 18. The opticalfiber coloring and curing apparatus of claim 17, wherein the coversection comprises a first axial telescope portion and a second axialtelescope portion, the second axial telescope portion being slidable atleast partially within the first axial telescope portion.
 19. Theoptical fiber coloring and curing apparatus of claim 17, wherein thecover section comprises a first half tube section and a second half tubesection, the first and second half tube sections each having asubstantially semi-circular cross section, the first half tube sectionand the second half tube section forming the first duct when the coversection is in a closed position.
 20. The optical fiber coloring andcuring apparatus of claim 17, further comprising a lead-in piecepositioned between the distribution seal and the cover section, thelead-in piece having an interior surface and an exterior surface, theinterior surface of the lead-in piece at least partially enclosing asecond bore capable of passing the coated optical fiber between thefirst duct and the first bore, wherein the cover section is a flat platemounted on top of the lead-in piece.